Improvement in fusible plugs for steam-generators



H. HILLER. FUSIBLE PLUGS FOR STEAM-GENERATORS.

No. 195,367, Patented Sept.18,1877.

PATENT QFFICE.

"QHENR H LEB, 'Or'MAn-onns'r En, GREAT BRITAIN.

" iMPRovinin -m ImFus BiiE PLUGS FOR STEAM-GENERATORS.

. p o mflj i t if Lettersl fatentNo- 195,367, dated September 18, 1877application filed I July 16,1877.

To all whom it 56mm.- Q 1 Be. it known that, I, HENRY .HILLER, chiefengineer of the National Boiler Insurance Company, of Manchester, in thecounty of Lan ratus, of which-the following is speci-lica- My inventionrelates to such fusible plugs as are formed with an inner cone, which issecured within an outer cone byme'ans of an interposin g stratum. offusible metal, which has hitherto been run in a melted. State into thespace between the two cones. When the said fusible metal has beenmelted, and the inner cone has thereby been released, it has beennecessary to renew both cones, or to remove both cones for repairs.

The principal object of my invention is to remedy this defect, and toenable the said inner cone, in'some cases, to be fixed within the outercone, while the latter is in position, without entering the steam andwater space of the boiler; and this I accomplish by so forming the partsthat the inner cone, with a coating or envelope of fusible metal, can besecured within the outer cone without removing the latter from its placewithin the steam-generator. In certain forms of the apparatusit isnecessary to enter the steam-generator to replace the part containingthe fusible metal; but it is not necessary to remove the part attachedto the generator. To prevent a portion of the fusible metal from beingmelted out in advance of the main body, I form aflange on the lower endof the inner cone.

To render my invention more clear, I have supplied a sheet of drawingsmarked with letters of reference.

Figure 1 represents a vertical section of one form of fusible plug asconstructed in accordance with my invention. Fig. 2 is a plan of theplug reversed to show the interior. Fig. 3 is a representation of a keywhich may be employed to remove and replace the inner cone, and Fig. 4 amodification of the device for screwing the inner cone into position.

In Figs. 1 and 2, A is the outer cone, which is suitably formed to screwinto a furnacecrown, or the part of a boiler, still, waterheater, orsimilar apparatus, to which the fusible plug is to be aflixed.

The upper part c of the outer cone is bored or formed to a conicalshape, and at the base .of this cone is formed a cylindrical part, d,

which ischased, or tapped, or formed with a screw-thread on the inside.The inner cone E is made partly conical and partly cylindrical in form.The conical part is turned to a conical form, or is left rough, or iscast or formed with recesses or with flat sides. I

, prefer to form a screw-thread on the cylindrical part of theinnercone, and, when so formed, the conical part may be turned, and need notbe formed with recesses or other means for holding the fusible metal.The base of the inner cone is formed with a flange, e, which is a littlelarger in diameter than the bore of the cylindrical part (1.

The envelope of fusible metal is represented by the dotted space betweenthe parts A and, E. This envelope is cast upon the inner cone E, and issubsequently turned and screwed or chased to fit and screw into theouter cone A; or it may be found to be convenient to cast the envelopeof fusible metal upon the said inner cone ina mold which would beconstructed to impart the required form to the outside of the saidenvelope, and to form the screwthread upon the cylindrical part thereof,thus dispensing with the necessity for turning the fusible metal to fitthe inside of the outer cone. The envelope may be cast separate from theinner cone, and be subsequently screwed upon the inner cone, in whichcase the inner cone would be formed with a screw-thread, as in thedrawing. It is necessary that the outer surface of the envelope shallfit the interior of the cone 0 with sufficient exactness to prevent theescape of water when the inner cone is screwed into its place within theouter cone. When so screwed into position the flange 0 covers the baseof the envelope of fusible metal, and prevents the direct action of thefire upon such metal.

In thecase of plugs as previously constructed, the fusible metalsometimes melts partially, so as to permit a slight escape of steam,which checks the complete fusion of the metal, and, the inner cone notbeing blown out, a sufficient outlet for the steam is not formed.

The flange 0 is intended to prevent any portion of the fusible metalfrom running out until the whole of it is fused snfliciently to permitthe inner cone to be blown out, the indicated defect in the ordinaryplugs being thus remedied.

The arrangements for screwing the inner cone E into position may bevaried. For example, the said inner cone may be formed with an internalcavity, a part of which cavity is of an octagonal form, as seen in Fig.2. A key (represented by Fig. 3) is formed to fitinto the octagonal partof the said cavity.

When an inner cone has to be insertedinto the outer cone A, it is simplynecessary to place the said inner cone on the key, to insert it into thepart A, and to screw it into position by turning the key. When an innercone has been blown out, a fresh inner cone, or the same inner cone witha fresh envelope, can be screwed into position without emptying theboiler, it being only necessary, under ordinary circumstances, to coolthe furnace sufiiciently to enable an operator to get the nner cone intoposition. a comparatively short delay being occasioned.

The cavity in the inner cone may be made of a square, hexagonal, orother form, or slots may be out or formed in the base, as in the case ofan example to be described hereinafter. The form and proportions of theinner cone and of the cavity in which it is fixed, and the form andarrangement of the screw-thread, may be varied.

Fig. illustrates a modification in the arrangements for screwing thevinner cone into position. The inner cone is formed with a shankprojecting into or toward the fire-box or furnace. The lower end of thisshank is squared or otherwise shaped to be turned with a screw, key, orspanner.

I claim as my invention- 1. The outer coneof afusible plug, providedwith screw-threads on the inside, in combina tion with the inner coneand its fusible-metal envelope, adapted to be screwed-into the outercone, substantially as described.

2. The combination of the threaded outer and inner cones with theenvelope of fusible metal, adapted to be screwed into the outer cone andonto the inner one- 3. The combination of the cone E, provided with therectangular collar 0, with the outer cone and the intermediate fusiblemetal, as and for the purpose set forth.

HENRY HILLER.

Witnesses:

J. HERBERT BEOWNE, EDWARD K. DUTTON.

